Optical elements are generally optimized for their optical characteristics, such as transparency or reflectivity in a desired spectral region. However, in many applications, an optical element may be exposed to mechanical stress. Therefore, some optical elements are coated with a material intended to provide improved mechanical performance, such as improved hardness. Unfortunately, the addition of a coating to an optical element can degrade the element's optical properties. Many coatings that provide a large improvement in mechanical performance also cause a large degradation in optical performance.
Therefore, there exists a need for coatings for optical elements that improve mechanical performance but do not significantly alter or degrade the optical properties of the underlying optical elements.